It is an object of the present invention to provide a controller for a machine tool and a five axis simultaneous control machine tool controlled thereby which can improve the machining accuracy in machining by controlling a driving axis including a linear axis and a pivoting axis.The controller comprises a detecting member 102 detecting a machining position where a pivoting axis is reversed in machining by the machine tool 1 based on the control data, an allowable position error setting member 103 setting an allowable position error Δ between a commanded machining position P1 and an actual machining position P2, an allowable acceleration deciding member 107 deciding the allowable acceleration about the pivoting axis based on a distance L1, L2 from the machining position of the reversed axis to a center of the pivoting axis and based on the allowable position error Δ being set, and a controlling member 108 controlling a velocity about the driving axis based on the allowable acceleration.